Photos and a video have emerged showing sea animals chained up inside underwater cages near the remote island of Kokoya, Indonesia.
Divers swimming in the area came across two cages that trapped two dugongs on the seabed.
The divers believe the trapped marine mammals are a mother and her calf, and that they had been caught by local fishermen hoping to profit by allowing tourists to take photos with them, The Sun reported.
One of the divers, Delon Lim, told the news website that the mother and baby were being held in separate cages.
Lim later told animal welfare website The Dodo that while the baby was allowed to swim inside its cage, the mother's movement was restricted by a huge rope.
The scars on the mother's tail and the wear and tear on the rope suggest that the animals had been restricted and trapped for several weeks.
"He asked for some money if we wanted to see the dugong or take a picture," Lim told The Sun, explaining that the animals were being used to attract tourists.
Lim and a fellow diver tried to convince the fishermen to free the dugongs.
He was quoted by The Sun as saying: "When we left the island, the fisherman had agreed to release them. But we were not so convinced he would, so we posted the video on social media."
The video drew the attention of animal welfare authorities who arrived on the island the following day only to find the dugongs still trapped.
According to The Sun, they were finally set free later that day.